This invention relates to aquaculture, and, in particular, to the use of growth hormones, especially bovine somatotropin (bST), to enhance the rate at which aquatic animals grow.
Fish is a recognized source of food. World-wide demand for wild-caught fish has lead to a phenomenal growth in the aquaculture industry. World-wide demand for fish continues to grow. Fish are found world wide, and can be fairly inexpensive where fish are plentiful. If fish could be grown more quickly, farm grown fish could be harvested more quickly than presently possible. This could increase the supply of fish and concomitantly reduce the cost of fish to consumers and reduce the threat of over fishing of wild populations of fish and the effects on the environment of such over fishing. A considerable amount of research has been conducted with aquatic animals, and in particular, with methods or treatments to increase the rate of growth of aquatic animals. Some of this research has focused on the use of growth hormones (including bST) and methods of administering growth hormones to fish. Fish have been injected with growth hormones and immersed in growth hormone solutions. Because of the configuration of fish muscles and skin, the skin does not readily close up at the injection site, and hormones injected subdermally or intramuscularly can simply be washed out of the fish. The injection of bST into fish thus has not been a successful method of administering growth hormones.
I know of two studies in which fish were treated with growth hormones: (1) Growth Stimulation of Juvenile Salmonids by Immersion in Recombinant Salmon Growth Hormone, Moriyama et al., Nippon Suisan Gakaishi, 56(1):31-34 (1990); and (2) Experimental Administration of Recombinant Bovine Growth Hormone To Juvenile Rainbow Trout (Salmo Gairdineri) By Injection Or By Immersion, Schulte, et. al., Aquaculture, 76:145-156 (1989). Both studies used low levels of growth hormone. In the former study fish were immersed in a solution containing 30 mg/l of BSA; in the latter study, fish were injected with 10 .mu.g growth hormone/g body weight. The method disclosed in the latter study (Schulte, et. al.) did not show a marked difference between the treated and control groups. In the former study, the authors concluded that immersion in rsGH may be useful as a method of GH (growth hormone) administration to accelerate the growth of fish in aquaculturc. However, there are advances that can still be made in the administration of growth hormones to fish, particularly in the manner of administration of the growth hormone to enhance or accelerate the growth of fish.